Thermoregulation

Question 1

How much heat production can be increased by shivering?

Answer 1

500% greater than resting levels

Question 2

What is the primary thermogenic tissue in infants?

Answer 2

Brown adipose Tissue

(BAT)

Question 3

Primary thermogenic tissue in adults

Answer 3

Skeletal muscle

Question 4

Net energy movement from warmer object to the cooler object

Radiation

Evaporation

Convection

Conduction

Answer 4

Radiation –> 60%

Evaporation —> 20%

Convection —> 15%

Conduction —> 5%

Raditation> Evaporation> Convection> Conduction

Question 5

Heat loss by transfer of photons

Answer 5

Radiation

* not heat loss to surrounding air

Question 6

Insensible water evaporation from the skin and lungs

Answer 6

Evaporation

1/2 is respiratory loss

minimized by humidification, covering exposed skin, using warm preps.

Question 7

Heat loss with contact with cooler object

*this requires direct contact

Answer 7

Conduction

*Insulation increases the resistance to heat loss

* minimize by using warmingmattress under patient, increase ambient temperature, forced warm air, warm solutions

Question 8

Heat Loss through moving cool air

*occurs when objects of different temperatures are in “contact” with fluid

Answer 8

Convection

Question 9

What is the primary terminal organ for cold sensation?

Answer 9

Krause’s end bulb

Question 10

What is the primary organ for warm sensation?

Answer 10

Ruffini’s corpuscle

Question 11

How does cold sensation from afferent temp peripheral sensor is transmitted?

Answer 11

Transmitted to spinal cord by small- diameter, myelinated, A-delta nerve fibers

Question 12

How does warm sensation from afferent temp peripheral sensor is transmitted?

Answer 12

transmitted to spinal cord by unmyelinated C nerve fibers

** bith sensations travel to substatntia gelatinosa if posterior horns of spinal cord –> anterolateral spinothalmic trat to thalamus and associated basal structures

Question 13

Where are the afferent temp central sensors located?

Answer 13

located in CNS and other core structures

base of brain, especially the hypothalamus and spinal cord, provides both cold and warm thermal input

Outside the CNS, central thermal input arises from receptors in muscles, as well as sphlanic and vagal afferents

Question 14

What is the most important mechanism for transferring heat between core and periphery?

Answer 14

Cutaneuous vasodilation

*heat transfer through convection as blood travels through tissues**

** vasodilation accomplished inhibition of centers in posterior hypothalamus responsible for vasoconstriction

Question 15

this is a major mechanism for evaporative heat loss

Answer 15

Diaphoresis

Question 16

how does the body respond to hypothermia?

Answer 16

body responds by increasing hear production and decreasing heat loss

Cutaneous vasoconstriction

Piloerection

Shivering and nonshivering thermogenesis

Question 17

How much does your metabolism decrease for each 1*C in body temperature?

Answer 17

6%

Question 18

Pathophysiology of Hypothermia

how much is the overall decrease in O2 consumption and Neurologic function?

Answer 18

Oxygen consumption: decreased 4% per each 5*C drop; O2 dissociation curve shifted to left –> O2 not released too easily

Neurologic function –> decreased mentation , cbf, O2 consumption and csf pressure

CBF anf O2 consumption decrease 7% for each C decrease in temperature

Question 19

Where does heat loss escape the most?

Answer 19

The head